There is considerable demand for the miniaturization of electronic devices in general and for cellular telephones in particular. On the other hand, there is increasing demand for electronic devices that include more and more features. Invariably, these demands result in a reduction in the display area, that is, the size of the display screen, or of the viewable area. A major reason for this being the necessity of maintaining a conventional keypad matrix arrangement for inputting data. Although the size and the spacing of the buttons that form a conventional keypad matrix arrangement are constantly being reduced as a result of miniaturization, there is a limit to their reduction. Moreover, with small buttons, or closely spaced buttons, there is a high likelihood of accidentally depressing an unintended button which is adjacent an intended button, or even simultaneously depressing two adjacent buttons thereby providing false input data. Moreover, since the buttons are depressed one by one for each input data, speed of operation is limited.
U.S. Pat. No. 6,441,753 discloses a multifunction key assembly for electronic devices. The multifunction key assembly has a button member having an upper contoured surface defining nine key regions, which in a preferred embodiment, are arranged in a manner consistent with the one through nine keys of a conventional telephone keypad with the central key region representing the five key of a telephone keypad and each perimeter key region represents the remaining keys. However, unlike the conventional keypad matrix the zero, asterisk and pound sign keys are missing. An auxiliary button may be representative of the zero key. Alternatively, each key region may serve multiple functions. For example, the five key region may operate as a conventional zero key upon a double-click. This option is suggested, but its implementation is not described. Whatever the case, the numeral zero cannot be entered through the principal mode of operation and therefore every time a zero that has to be entered will disrupt the smooth flow of data input.